Retort



Feb. 1944. J. s. ELLIOTI' RETORT Filed Sept. 6. 1939 Invenior JwmsS/Efmtt Attorney the retort is described in'detail.

Patented Feb. 29, 1944 UNITED STATES PATENT OFFICE amour James Scott Elliott, Greenville, Ohio Application Sentembet 6, 19-33, Serial No. %93,610

2 Claims.

The invention relates to improvements in underfeed stoker retorts of the type in which coal or other fuel is fecl into the retort by an horizontal helical screw and dischargecl vertically by displacement. the entire combustion of the fuel takes place in the combustion chamber, or fire pot, above the retort and the coking of the fuel, particularly of strong coking fuel, is such that the pieces or small chunks of fuel adhere strongly one to the r other which results in the building up of a structure, or coke tree, which often reachee relatively great height before it collapses on the .fuel bed, thus producing a fuel bed which lacks uniformity, and an inefficient combustion of the fuel.

One object of the present invention is to provide a retort of such a character that an initial, or partial, combustion of the fuel will be effected in the retort itself, thus minimizing the coking of the fuel and preventing the adherence of the ,pieces or chunks of` fuel 'one to the other or so reducing such adherence that the coking structure will be Weak 'and will collapse on the fuel bed before it reaches any substantial height,

A further object of the invention is to provide such a retort with openingssto admit air to the lower part of the fuel chamber therein .and to discharge the air upwardly 'through the iuel, to induce initial combustion of the fuel in said chamber.

maintain' the latter at such a temperature that the coking fuel will not adhere zthereto.

Other objects of the invention may appear 'as In its preferred form the improvement consists of placing the air openings around the discharge of the helical screw 'so that immediate ignition, roasting or partial combustion of the coal 'is Secured while the coal'is 'agitated and churned by' action of the helical screw in :passing from horizontal to' Vertical inoti'on; This location of the air openings also'makes sure of cooling air currents at the discharge end of the helical screw.

One form of the invention is illustrated in the accompanying drawing, in which Figure 1 is a plan View of the retort with lid removed: Figure 2 is a vertical section of the retort along line AA in Figure 1: Figure 3 is a perspective View of the retort; and firebed in phantom illustration of coking structures.

In the usual form of retort` pressure.

In the drawing I 'have 'illustrated the preferred form of my retort and have shown the same as a cylindrical structure having a bottom wall or base 8, an inner wall 9 forming within the same a 'fuel chamber 3 which is open at its u per end, and an outer wall lo spaced from the inner wall to form between said walls an air channel or chamber 5. The topjplate or lid H closes the upper end of the air channel` or chami ber 5 and has an opening !2 through which 'the retort chamber 3 communicates withthe combustion chamber, or fire box, of the furnace, i

this opening being preferably of a diameter ap# :proximately equal to 'the diameter of the retort chamber. A fuel supply Conduit 5 extends through the walls 9 'and !U and a feed screw I feeds the fuel throughthe conduit 6 into the retort chamber 3 and forces the same upwardly through the retort chamber into the combustion chamber. Due to the angular relation of the inner vertical wall to the bottom wall of the retort there results a relative displacement of the pieces of fuel as the mass of fuel passes through the retort to the combustion chamber, which p displacement tends to break up any adherence of the pieces one to the other. The air chamber or channel 5 is provided with means, such as an inlet !3, for connecting the same with a source of supply of air, which, if desired, may be under The inner wall 9 is .provided with an opening or openngs throughwhich air from the channel 5 may enter the retort chamber 3 near the 'bottom of the latter and, in the present instance, the innerwall is provided on each side of the fuel conduit 6 with a series of Slots 4 spaced vertically one above the other. As here shown,-these slots decrease in vertical width toward the outer side of the wall.

The steel helical screw l revolves forcing coal rpast discharge end 2 into chamber 3 where by displacement it is forced to rise up and out of chamber 3. The cast iron wall of chanber 3 has openings l connecting to air chamber 5 through which air passes into the coal voids as .soon as the coal leaves end of helical screw l at 2. This gives immediate ignition, roasting or partial combustion of the coal. This combustion continues as the coal` is agitated and churned in passing forward and upward out of the top of the retort chamber 3. This churning burning movement of the coal prevents the strong natural cementing together of the coal particles, resulting in a Weak coking effect with Weak ccking structures 1 breaking down more rapidly from their own weight. Hence a more uniform firebed and more eflicient combustion of the coal. As is usual in an underfeed furnace the fuel bed builds up around the retort and the surface thereof slopes upwardly and outwardly. The mass of coal which moves upwardly through the retort, in a more or less loose condition, tends to follow the sloping surface of the fuel bed and such coke structures as may form either move along that surface or collapse onto the same before they have reached any substantial height. In Fig. 3 there are shown two successively formed coke structures which have assumed inclined positions in which they would rest on said fuel bed or be very close to the sloping surface thereof and about to collaipse. Successive structures rise in diiferent parts of the retort and thus Collapse on different parts of the fuel bed and automatically maintain a. substantially uniform fuel bed.

As these coke structures rise and move toward the wall of the retort chamber they may at times force ashes or small pieces of coal into the openings of the wall, thus tending to clog the same, but as soon as the coke structure has moved beyond the clogged openings or has been consumed the air from the channel will blow the ashes from the openings into the retort. The inwardly diverging walls of the respective openings offer but little resistance to the inward movement of the ashes and any pieces of coal which have tightly wedged in the opening will be quickly consumed to such an extent that they may be easily dislodged by the air.

Also, the location of the air openings 4 near the screw discharge 2 creates cooling air currents in air chamber 5 adjacent to the screw dischargc, and these air Currents, together with the air which is discharged from the openings 4 across the inner end of the fuel conduit, cool the screw thus avoidng coking coal adhering .to the discharge end of the screw as from l to 2 in Figure 1 Older forms of retorts separated the air openings from the screw discharge as far as possible to prevent smoking back in the screw tube 5, coking coal from adhering to discharge end of the screw and to secure higher firebed levels; hence requiring additional devices to secure adequate firebed agitation in preventing coking structures. These devices at the base of the fire have high maintenance and frequent failure.

I am aware that prlor to my invention stoker retorts have been made with many arrangements of coal and air discharges. I therefore do not claim such combination broadly; but I claim:

1. In a retort for swpplyng fuel to the combustion chamber of an underfeed furnace, a bottom wall, a substantially cylindrical wall extending upwardly from said bottom wall and forming within the same a chamber having an open upper end to communicate with said combustion chamber, an outer wall extending about and spaced from said cylindrical wall to form an air channel, said channel having means' for connecting the same with a source of supply of air under pressure, a substantially horizontal conduit extending through said outer wall and said cylindrical wall near said bottom wall, terminating adjacent said cylindrical wall and exposed to the action of the air in said channel, a feed screw in said fuel conduit terminating adjacent the inner end of said conduit and operable to feed fuel into said retort chamber and force the same upwardly through said retort chamber to said combustion chamber, said cylindrical wall having a plurality of circumferential series of relatively large slots therethrough to admit air from said channel to said retort chamber, the lowermost series of slots being located close to said bottom wall and the upper-most series of slots being located in a plane adjacent the top of said fuel conduit, thereby initiating combustion of said fuel while it is close to said bottom Wall and maintaining said combustion as said fuel moves upwardly in said retort chamber, the angular relation of said cylindrical wall to said fuel conduit causing the agtation of the burning and partially consumed pieces of fuel and materially reducing the adherence of ;pieces of fuel one to the other, a part of said slots being located adjacent to and on opposite sides of said fuel conduit to cause the relative cool incoming air to circulate in contact with the inner end of said fuel conduit.

2. In a retort for supplying fuel to the combustion chamber of an underfeed furnace, a bottom wall, a substantially vertical wall extending upwardly from said bottom wall and shaped to form within the same a chamber having an open upper end to communicate with said combustion chamber, an outer wall extending about and spaced from said vertical wall to form an air channel, said channel having means for connecting the same with a source of supply of air under pressure,` a substantially horizontal conduit extending through said outer wall and said vertical wall near said bottom wall, terminating adjacent said vertical wall and exposed to the action of the air in said channel, a feed screw in said fuel conduit terminating adjacent the inner end of said conduit and operable to feed fuel into said retort chamber and force the same upwardly through said retort chamber to said combustion chamber, said vertical wall having a plurality of circumferential series of relatively large openings therethrough to admit air from said channel to said retort chamber, the lowermost series of openings being located close to said bottom wall and the uppermost series of openings being located in a plane adjacent the top of said fuel conduit, thereby initiating combustion of said fuel while it is close to said bottom wall and maintaining said combustion as said fuel moves upwardly in said retort chamber, the angular relation of said vertical wall to said fuel conduit causing the agitation of the burning and partially consumed pieces of fuel and materially reducing the adherence of pieces of fuel one to the other, a part of said openings being located adjacent to and on opposite sides of said fuel conduit to cause the relative cool incoming air to circulate in contact with the inner end of said fuel conduit.

JAMES SCOTT 'ELLIO'I'L 

